[Haskell-cafe] Control.bimap?

[Tony Morris]

Check out Control.Lens on hackage.

On 13/12/12 07:54, Gregory Guthrie wrote:
>
> I found a nice idiom for a graph algorithm where the pairs of nodes
> representing links could be merged into node lists by something like:
>
>     ns = nub $ map fst  g    --head nodes
>
>     ne = nub $ map snd g   -- tail nodes
>
>  
>
> And found a nicer approach:
>
>    (ns,ne) = (nub***nub) unzip g
>
> Or perhaps:
>
>    (ns.ne) = bimap nub nub $ unzip g    -- from Control.Bifunctor
>
>  
>
> The SO reference I saw described bimap as a way to map a function over
> a pair, and it seemed like a great match, but I cannot find the bimap
> function, and cabal reports no package Control.Bifunctor.
>
> ??
>
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-- 
Tony Morris
http://tmorris.net/

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